Sports equipment for fitting to the feet, for example inline skates, roller skates, grass skis, skateboards or snakeboards, are becoming more and more popular. There is a need to determine the sports achievements performed with such sports equipment, for example the distances travelled or the speed reached (current speed, maximum speed, average speed).
A bicycle is known from U.S. Pat. No. 4,689,557 wherein the speed measurement can be relised by means located in the wheel axle.
The construction described in this publication can, however, not be used in the region of the substantially smaller wheels for roller skates and roller boards as, for example, the signal generated has to be picked up by means of a very complex signal pick-up construction.
A bicycle is known from JP 62-177 453 A which determines the speed via a cyclometer comprising a rotating magnet and a stationary sensor. The mechanism described therein is, however, not suitable for roller skates and roller boards which are exposed to extreme shock strains.
A road skate is known from DE-GM 92 09 825.8 with a travel computer which is fitted to the boot of the road skate. To transfer data from rollers of the road skate to said travel computer, a friction wheel is provided which acts together with a driver wheel attached to the roller suspension. This mechanism is considered very complex and susceptible to breakdown. In addition, it has a large construction.
It is known from DE-GM 296 06 965 to provide a roller for roller skates with a magnet and a coil to generate an induced current to feed a light emitting element. This publication does not deal with the measurement of achievement parameters of a user.
It is known from DE 44 44 315 A1 to provide on an axle fixed to a roller a dynamo to generate current to operate a light. This mechanism also proves to be very complex in practice, with, in addition, a strong friction force which hinders progress being produced by the dynamo. This mechanism is not suitable for rollers which revolve around a non-rotating fixed axle.
Finally, a roller skate is known from German utility model DE 296 16 211 U1 with a frame, a boot which can be connected to the frame and rollers mounted on or in the frame, in which on one of the rollers a contact maker is disposed and on the frame a contact pick-up coupled to the transmitter is disposed, with a receiver equipped with a display fitted for the display of achievement data, which receiver can be taken along by the roller skate, being allocated to said transmitter.